SQL Server Transact Basic to Expert - Decreasing a date and time by 30 Mins using SQL query

This blog shows how to do an decrease a date and time value to 30 mins in the output using SQL Query

Example:

SELECT DATEADD(mi, -30, '2011-02-02 22:30:00.000')

The expected result would be 2011-02-02 22:00:00.000